Everyone is an expert when it comes to weight and weight control, and I’m no exception. I am what’s known as an “exercise theorist.” That is, I ascribe to the lay theory that sedentary lifestyle is a major cause of obesity, and that regular exercise is the cure. That’s one of the reasons I show up at the gym most days — and nag others to come with me.

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So what are the consequences of such lay theories? And more important, what are the consequences of embracing the wrong theory? University of Michigan psychologist Brent McFerran has come to believe that our naïve theories of weight control are not entirely harmless, and indeed that they could undermine our own efforts to achieve a healthy weight. Working with Anirban Mukhopadhyay, a colleague at the Hong Kong University of Science and Technology, he has run a series of experiments around the world to explore this possibility.